Means for stopping pulsations in centrifugal compressors.



R. H, WCE.

Inu/emr.' Richard H. Fice,

WMM

RICHARD E. RICE, OF LYNN, MSSCHUSETTS, ASSBGE'GR TG QEIIERAL ELECTLG CMPANY, A CGHPRTGI? 0F Y-EK.'

MEANS FOB. STOYPING IULSATIONS IN CNTBFUGAL CGMPRESSORS'.

Specification ef Letters Patent. l Paie'nd June 27, 1916.

Application filed August- 14, 1913. Serial No. 784,713. Y

l Tov all 'whom it may concern:

Be it known that I, RICHARD H. Rien, a citizen of the United States, residing at Lynn, county of Essex, Statee Massa- 6 chusetts, have invented certain new and use ful Improvements in Means for Stopping Pulsations in Centrifugal Compressors, of

- which the following is aspecilication.

Centrifugal compressors as commonly con- 10 structed comprise one or more stages, eachvariable speed to cause a constantV volume ofY fluid to be delivered. These compressors .usually discharge into a receptacle having considerable volumetric capacity over and above that of the compressor itself. Such a receptacle may be the pipe line to which the compressor is connected, blast furnaces or other apparatus connected thereto. Such 80 compressors operate on what is termed a rising characteristic at light loads, meaning .fthereby that an increase in the volumetric output is accompanied by an increase in pressure. This peculiarity is wholly or at least in a large part due to the action of the means for converting velocity into pressure, -said means recei vin and acting on the fluid from the impellere'fore it enters the pipe line or other apparatus connected thereto. o The use of said mea-ns, while having a very important function in the production of -\co mpressed fluid gives rise, under light load ixrditions, to what is commonly known as pulsation or surging of the Huid undergoing compression. The loadvat which pulsation begins varies with dill'erent compressors, but

as a general proposition it may be stated to be from :betweento 40% of full load.

The point at 'which -pulsation begins is genA 5o orally known as the breakdown point. p The intensity of these pulsations varies with `\dill"erent compressors, with different eapaciti'sin the pipe line and apparatussupplied thereby, and frequently `with changes in si.. climatic conditions. In all cases they arev highly objectionable le will be readily lip-- pieciated. 1-

My invention has for itsobject to overcome these highly objectionable surgings or pulsations in compressors of the types referred to herein, and to that end I provide a valve on the inlet side of the compressor for throttling the admission. This valve should preferably be wide open from 'full load down to the breakdown point, after which it must throttle the passage through the conduit by an amount suilicient to prevent pulsation. This requires that the throttling increase as the volume admitted` to the compressor decreases. Y

I have discovered that in order to prevent pulsations the throttling required from the breakdown7 point to no load is not a straight line function of the amount of fluid which the compressor is takingrce., of the load, but that it is of such a nature that the throttling must increase more rapidly than the change in load. L

More specifically, therefore, the object of my invention is to provide an improved -apparatus which will give the desired characteristic Imovements to thefthrottling valve.

This apparatus is in addition to the gov-I erni-ng meehanismwhieh regulates the speed of the motor or prime mover employed to drive the'compressor. In the accompanying drawing which illustrates one of the embodiments of my invention, Figure l is a vertical section showing my improved mechanism; Fig. 2 .is a partial vertical section taken at'right angles to that 1 of Fig. l; Fig. 3 is a side elevation showing a weight for vadjusting--the action of the mechanism, and Fig. Liis an' end elevation of a centrifugal compressor showing the mechanism inposition. y j

9 indicate-s the casing of thecompressor havingan inlet conduit l0 and .a discharge j conduit ll. Located' ivithinthe casing is a bladed impeller 'l2 and stationary discharge vanos i3 which surround the iinpeller and act, as means to convert velocity of lthe fluid received. from the impelleiinto pressure. Between the vanes are passages that iirst converge end then diverge or they may be wholly divergent; this will depend upon the conditions of o ration as to pressure. Air or other elastic fluid is delivered to opposite sides of tin` impeller by chambers which oinnninicate with the supply' ion pipe 14. The impeller .is'mounted on a shaft 15 which'is provided with suitable hearings and is driven an electric motor or prime mover. Secured tothe inlet conduit is a downwardly turned elbow, the lower end of which is secured to an enlargement in the supply pipe.

The enlargement Vcomprises two conical members 17v and l 8.whose enlarged ends are securedA together by bolts. Mounted in the upper ylindrical portion of the conical .member 17- is af butterfly valve or damper 1 9 otally attached a rod 24. The lower end of ing' the point of connectionof-the rod Q4' sition bfy the lock nut 27.

the rod is held in position and guided by the spider 25 which is either cast integral with the conical member' 18 or attached thereto. Threaded on'the rod '24 is a volume measurcr made in the formel a floating disk 2t? that is acted upon by the flowing fluid. That is to say, the float is raised or lowered by changes in the volume of fluid entering;r lthe compressor, which float. inturn l Opens or closes the valve l5)y thereby throtr tlingr the fluid by an amount Adepending;

, l upon the position of thefloat. The an'iount ofthis throttling is 'relatively greater at Alight vloads than' it heavy and should he suf- 'ficient especially at' light 'loads to prevent pulsations'hy slightly modif 'ing the characterist-ic'of the. compressor;-

' c., changing it.v from a" rising 'to an ap proximatelyllolizontal one. The arrangement. is preferably such that the throttle. valve is held fully:

open for Vall loads above the V brca'lcdmvn point of the compressor. The floating;f disk which' is threaded on the rod is held in po- .'h'e' lug 9:2 'cx- Vtends radially with respect fx the center of the valve 19 and the holes 4.3 therein permit of relative adjustment olf the valve and floating;r disk 2li, That is to say, by changand valve a given movement of the tl'oat will fcause the valve lto open to a'greatcr or lessi extent.

Rive-ted or. otherwise Secured to the butterfly valve is a weight 3() which may he composed ,ofl a number ofthin metal Strips, said weight servingto counterhalance wholly or in part the weight. of the rod 24 and float 2.6. By' increasing or decreasing' the number of platesI or changing;r their position the effectief the weight on the flow measurer can he changed. Mounted on the lever portion 21 of the valve spindle is an adjustable weight 3l by means of which the action of the parts can be changed. or

may he of any suitable type, and may hev provided with any' desired `form of governing mechanism for ntrollingits' speed and also that of the inn'wlle'rg'.

Assumingthe weight" 3 1. isv set for 'any predetermined operating condition, the 'fluid vas it flows into .the-.compressor aetaon the under side of thevolumeyineasurer. or float 2G and raises thesame -hy agreater or less amount. This causes thefthrottle.. valve 1S) to assume a position corresponding to the amount of fluid flowin f. j

The connection 'between the s'and thevalre is preferably so'adjnsted that for all flou-'s abovethe,breakdown pointl the valve is wide open. lf nowthe-flowfdecreases to the brealnlown A point tlien the ytloatfwi'll lower a little, thus tlirottling. theinlet to the desired degree. lf the flow deer ases still more, then the float'nill further vclose thc valve. As already pointed ont, however, this Yadditional' amu'untgof tlifrottling,r necessary to prevent pulsaiionat the. lighter load most -begreator'in'. proport'ion to the load changeas the load lt-crea:

an upwardly opening,(-o nc a` 18; and. arranging thc volun'ie meas-uren' shown, I 'reduce oraroid thethrottlirlgiactioii which would other-.mise talge'place alt he; loads. Thatis to say, as thef liu\.asixren.moves upward it occupies a positionin theconc of larger dianwngr` and hence a great-er space vis provided 'for-the fluid lictiveen it'and the surroundingr wall ofthe conduit-f lu other words the' relation'of the volumev nieasurer 2G with respect to the v.cir:lar, fed lower. end of the conical part. "17 such that-:it full volumetric flow the .said nuasn'rer occupies Va position where it will not thiiit'tlcthe passage of fluid flowingthrough the'compressor. Looking: at, the,matteranothei way, thc volume measurerlunderthese conditions is above the throttling at nrie. the measurer is thusl positioned-the throttle valve.

Vis wide open and hence permits free flow of the fluid lmdergoinig', compres` on.

By myimprovcd ucture f\,' l\ eren the valve and the floatare. formed-separately and connected .togetlnirieaclrijean hemadc to obey a sepa rate law ir its mm'zements. and- I can thas obtain any ld @characteristic for the throttling of th' v e" 1n accordance with thi' )visions of the patent statutes, I have de riued the principle of operation of my invention; together :with the apparatus which l1 n iow" consider By using.

los

to representthe` best embodiment thereof; but I desire to have Vit -luiderstood that the apparatus shown is onlyi illustrative, and that theinvention can be carried out hv other means.

which is separate and distinct from' `the valve, means for connecting. the volume'-` mensurer tothe valve, whereby the volume measurer may follow a different law in its movements from that which -the valve Vfo'llows.

2.v The combination with a centrifugal compressor having un inlet und :in outlet,- of means for stopping pulsations at light loads comprising afloat whose position is ci'in'nged by changes in volume' of the 'fluid passing through the compressor, a vnlvevvhich acts to throttle the postage of' uid through the compressor, and means connecting the float to the valve for communicating movements of the float to the valve.

3v. A centrifugal compressor having an inlet and an outlet, in. combination with :i

float 'located in said inlet which is moved in response to changes in volume of the fluid entering the compressor, n throttle valve located between the oat and impeller of the compressor` and means connecting the {io-(1t -to the valve, said menne being arranged to impart relatively different/amounts of movement from the Afloatf to the valve. varying in :iccordnn'ce with the lijad. o Y

4. The combination with :i centrifugal compreor having an inlet and nu outlet` of means for stopping pulsations at light londe comprisingr a device iesponsive to and moving in accordance with variations in the volume of fluid passing throughthe corn- `pressor a valve lwhich is separatevand flis-A tinct from said` device foi" throttling Athe a different' inw in its movements from that which the vnlvcfollmvs, a spindle for the volvo having :in firm, and :in edjustuhle weight Amounted on the arm.

ii. A centrifugal compressor mvinf; nn inlet und an outlet, u conical memherfin the inlet` a volu; iemeasurer located in the memher neer its enlarged end, a. throttle vzilve pivot-oily Supported in the inlet on the compresrsor of the measurerfand a connection extending from theinensurer to the valve for opening the latter as the mcasurer movesv outvvrin'l fromY the enlarged end of the conical member. v

7. A centrifugal mpressor having an inlet and an outlet', a conical memberin the inlet, a volume measurer'locted in the inemher car its enla'iged'end, a. throttle valve pivotnlly supported in the inlet ontlie compressoiside of the measurer, a rod which' connect-s the measurer and the valve,` und n spider which engages the rod and acts as a guide' for it und the measurer. l

A centrifugal compressor havingr an inlet and nn outlet conduit, in combination 'with a volume mensurer in one ofthe oonduits, a menne-located in one'of the conduits for throi'tiing' the Yfluid iloWingthroughthe compres r at light loads, means connecting the volumeneasurer to the valve vwhereby the volume ineusurer may follow different inw in i'zs movements from that which' the `valve"ollmne.l :ind means formed in one of the conduits and cooperating with the nieesurer to permit 'fu-ll volumetric flow of the duid around the measurer at' h'eavier loads. Y

il. A centrifugal compressor having an inlet and an outlet, incomhination with a' volume incnsurer, :i valve forthrottling the fluid flowing through the compressor at light loads., meins comieeting the'. volume. Y

ments imparted to the v'ziive'. oy the volume measurer may haar any desired'relatxon .to

lthe movements of the rnensurer` and an enmeasure-r to the valvewheroby the moveheavier .loods to'prevent the same from throt- In combination, n ,conduit lin-'ving a` tronto-conical section and a converging sec tion", n float in the frusto-conic-l section, a vnlie located heyondthe converging section1 and i connecting, mezirnslhet'ween the valve and 'float whereby the vulve will be moved hj? the float ns the latter moves from :L smaller to a larger part of said frustoconicui section. l.

1l. in combination, n conduit having a `diverging' section nod a converging section,A u float-located in the divergfng section; :L

butterfly .valve located bevond thefcouvergi Y ingr section` n rod pivot-illy attached to the vulve und having said ijlont ndJ'ustahly mounted thereon` said valve being moved hy in flow of Huid in the conduit.

combination, n conduit having a nog und :i converging section, a Vfloat jointed ijn oiiverffing sectionE a butterfly linut :is changes its position with,

A and carries said float between its ends, and

valve bivotally supported in the conduit be- I In `witness whereof, I have hereunto set youd the converging sect'ion.l a rod that is my hand this 12th day of August, 1913. plvotally attached to the valve at one end RICHARD H RICE a guide for the rod in which it is free to VVitnesses move longitudinally in response to move- FRANK G. HANIE, ments of the float. JOHN J. MQKENNEY. 

